The purpose of this project is to improve our understanding of ways in which drugs may alter centrally mediated neurotransmission and to develop better pharmacotherapies for neurological disorders. Topics currently under investigation include: (1) the potential role of dopamine autoreceptors and the striatonigral "feedback loop" in regulation of dopamine activity and mediation of dopamine agonist effects; (2) the role of GABA afferents to the substantianigra and consequences of GABA agonist administration (3) the role of cholecystokinin (CCK) in dopaminergic function; (4) effects of neurotransmitter agonists and antagonists on the activity of globus pallidus neurons and (5) mechanisms involved in endogenous regulation of glutamic acid decarboxylase activity.